Apparatus for the heat treatment of fabrics



Jan. 5, 1954 c. KLUG APPARATUS FOR THE HEAT TREATMENT OF' FABRICS Original Filed Jan. 22, 1949 Patented Jan. 5, 195.4

APPARATUS FOR THE HEAT TREATMENT OF FABRICS Clarence Klug, Los Angeles, Calif., assigner, by mesne assignments, to Alexander H. Kerr and Company, Incorporated, Los Angeles, Calif., a corporation of Nevada Original application January 22, 1949, Serial No.

Divided and this application December 23, 1949, Serial No. 134,717

2 Claims.

My invention relates to the 'continuous processing of materials and more particularly to a novel apparatus for the continuous heat treatment of synthetic fabrics, such as glass fabrics or other organic-liber fabrics.

The fabrics with which the invention is partioularly concerned are made of small filaments wound into strands or yarns which are then Woven, knitted, or otherwise entwined to form the plastic interlaced or interlinked yarns producng a substantially definite pattern or texture. In referring to a strip of such fabric, I have reference to a relatively long length thereof such as is produced in the usual textile mill, the fabric being usually rolled or bolted in the mill preparatory to being made into the ultimate manufactured products.

Before the filaments are formed in the strands, they are often coated with an organic size which performs the function of holding the filaments together in the strands and to give some degree of protection to the filaments during the textile operations. This organic size must be removed from the textile product and it is an important object of the present invention to provide a novel apparatus for heat-treating such textile products to remove this size.

es explained in my copending application, lSerial No. 72,124, now Patent No. 2,633,428, entitled Material Treatment, of which the presfent application is a division, the removal of this size is a particular problem in the treatment of glass fabrics where it has been conventional to Vroll long lengths of the glass fabric on perforated steel mandrels to produce large rolls which `are slowly heated in a closed oven for many hours in an Iattempt to volatilize the size. Such a batch treatment is expensive, unreliable, and never subjects all portions of the rolled fabric to the same degree of treatment. If the temperature is raised too rapidly, the size will spontaneously ignite to raise the temperature inside the roll excessively.

As explained in my copending application, supra, I have found that the fabric can be moved relatively rapidly through an appropriate heating zone in which there is an abundance of oxygen to effect progressive heating of the fabric which can be employed to remove the size; to relax, kink, or set the yarns in their sinuous or bent forms in which they are present in the fabric; to produce a fabric of uniform strength and properties; etc.

It is an object of the present invention to provide .a novel yfurnace construction particularly Z adapted to the treatment of such fabrics and in which the heat is radiated toward the fabric While moving through the furnace.

Another object of the invention is to provide a furnace into which the fabric can be continuously moved and from which the fabric can be ycontinuously withdrawn, the fabric being subjected to a predetermined tension while subjected to the furnace temperature.

Another object of the invention is to provide an apparatus which avoids whipping or undue stretching of the fabric while passing through the heating zone of the furnace. In this connection, it is an object of the present invention to move the fabric through a medial zone of an upright furnace to maintain the fabric substantially in a single plane as it traverses the heating zone.

Another object of the invention is to provide an apparatus whereby the fabric can be subject both to a heat-treating step and to subsequent treating steps. As explained in my copending application, supra, it is often desirable to treat glass fabrics with a silicone-type material to increase its hand or to apply thereto an unsaturated chromium complex or `an unsaturated silicone to make the fabric excellently suited for use with the low-pressure laminating resins. In other instances, it is desirable to color the fabric after heat treatment and as a part of a continuous process involving such heat treatment. It is an object of the present invention to provide a continuous-type apparatus for passing a fabric through a heat-treating zone and through one or more of such subsequent processing steps.

Further objects and advantages of the invention Will be evident to those skilled in the art from the following description of an exemplary apparatus, described with reference to the heat treatment of glass fabrics by way of example. Such treatment of glass fabrics has been selected for illustration because of the difficulties involved in processing such material to remove the size, this operation being performed in the present invention by a burning of the size by a surface llame, the apparatus controlling the movement of the material so that this surface name is maintained in a selected zone of the furnace.

Referring to the drawing:

Fig. 1 is a diagrammatic representation of certain parts of the equipment and illustrates schematically the sequence of steps which are performed While the fabric is moving continuously;

Fig 2 is a horizontal sectional view through the furnace of Fig. 1, taken as indicated by the arrows 2-2 of Fig. 1;

Fig. 3 is an enlarged fragmentary view of a portion of the furnace, viewed as in Fig. l and showing one of the heating elements; and

Fig. 4 is a fragmentary elevational view of such heating element, being taken in the direction of arrow 4 of Fig. 3.

It is usually desirable that the length of fabric produced in the mill be rolled on a drum or roll, rather than being fed directly into the apparatus of the invention This is because the rate of production of the fabric is very limited and because the present process is capable of handling fabric at speeds far greater than those at which conventional textilelooms can operate. Correspondingly, Fig. 1 shows the present process as starting with such a drum or roll, indicated by the numeral I0, this roll being rotatably mounted in any suitable manner in the framework of themachine.

The strip of fab-ric is fed between pay-off rolls II and then around tension bars or' rollers I2 and I3 between which the fabric passes over a spreader bar I4 which serves to flatten the fabric and which may be an arcuate plate or a rotary structure.

The fabric then passes under a guide roll I5 and centrally upward through a. heating Zone IS of an oven or furnace Il, passing then over an upper guide roll I8. The lower guide roll? I5 is freely rotatable in brackets I9 carried by a shelf. 20 secured to furnace-supporting legs 2I. The upper guide roll IS is freely journalled. in brackets 231 mounted` on an upper framework 24 of the furnace I'I. rlhe guide rol-ls I5 and I8 form a guide means for the fabric and are located at guide positions respectively beyond the ends of the heating zone..

During the movement thus far described, the fabric traverses a heat-cleaning zone 25. It subsequently passes through a cooling zone 25a, av finishing zone 2B and a supplementary finishing zone 21, through equipment which will be described in greater detail hereinafter. Suice itto say here that, in the finishing zone, the material passes between drying rolls or drums` 28 and 29 and, later, between take-up rolls 39,. being then. wound, as a finished fabric, on a roll 3|.

It is important to the invention that-the section of fabric within the heating zone I Ii shall be subjected to a predetermined tensile' stressy to prevent undue elongation while in heated condition. The invention contemplates that the fabric shall be fed tov the heating zone at a controlled rate and that this fabric be withdrawn from the heating zone at an identical rate, with little tension being applied tothe fabric in the heating zone because of the drive means for the fabric and with tension from this source controlled by the action of the tension bars or rollers. I2: and I3 and the spreader bar I4 and the speed of the drive means'. To accomplish this, Fig. 1 diagrammatically shows a variable speed motor 33 cennected by any suitable gear reductions, not shown, to drive at substantially equal peripheral velocities, the pay-off rolls- Il, the drums 28 and 23 and the take-up rolls 30. The operative connections from the motor are. diagrammatically shown respectively by dotted lines 34', 35 and 36. If desired, the drum 3 I: can similarly be driven from the motorl 3-3 through a suitable friction clutch.v

In the preferredembodiment, the furnace I1- includes an outer housing 40 enclosing a mass 0f) insulating material 4I which may be built up of bricks or masses of material capable of withstanding the high temperatures contemplated. The. insulating material preferably surrounds the heating zonesY I6 on each of the four sides but provides entrance and exit openings @E and i3 respectively at the lower and upper ends of the heating zone. To adjust the degree of access of these openings'. 42" and 43 to the surrounding atmosphere, I prefer to provide an adjustable damper means. For example, blocks of insulating material 45 and 4t are disposed to move above the upper end of the heat'ng zone It, being sepa-rated4 by a space 4? through which the fabric moves without touching either of the blocks. To acl-just the sizeof the space 4l, I have shown a shaft '8 with oppositely-threaded sections respectively extending through portions i9 and Fifi of the two blocks. This shaft may be journalled and held against longitudinal movement by a bearing connectedV to the. upper framework 2t and may carry av handle 52 which, 'when turned, changes the width of the space 4l.

Preferably, although not essentially, the lowermost end of the heating. zone I6 is similarly partially closed by adjustable. blocks 55 and 5E through the means of a double-threaded shaft 5l anda crank 573.

Suitable heating elements, are disposed on opposite. sides of the heating zone I6. and preferably heat this. zone and the fabric moving therethrough primarily by radiantl heat directed to ward both sides of the fabric. As best shown in Figs. 2, 3,. and 4, these' heating elements are preferablyl of the electrical type and are indicated by the numeral 60. Each of these heating elements 6U is shown as including a Nichrome ribbon 6I wound in zig-zag fashion between ceramc posts 62 suitably imbedded in or carried by the insulating material 4I and providing heads E3 holding the ribbon in'v place against inward displacement. I. preferv to employ a plurality of such heating units positioned one above the other on each side of the heating zone, although other arrangements can be used without departing from the spirit of the invention. Preferably, the heating unit should be relatively close to the fabric. In a typical large-scale installation, such as illustrated diagrammatically in Fig. l, the distance between the heating elements may Well be in the neighborhood of about S. The width cf the heating zone I6 should be suiicient to accommodate the widestv fabric to be processed. The length or height of the heating zone will depend, in part, on the desired speed of the fabricv and upon other factors to be mentioned hereinafter. In practice, I have successfully employed ovens as small as 1 in height or length up to S or more and even longer ovens can be used. The furnace can be used. horizontallyv if the spacing between the guide rolls I5 and I8 is not too great so that the tension, necessary to maintain the fabric in a horizontal plane will not cause permanent elongation or stretching at the temperatures employed. On the other hand, a vertically-disposed heating zone is distinctly preferable and, with such disposition, it is distinctly preferred' that the fabric move upwardly through the heating Zone rather' than downwardly therethrough.

In practice, I prefer to operate each of the heating elements' at substantially the same teniperature but, if desired, the heating units at different elevations may be at somewhat diderent temperatures. There is a temperature gradient in the lower portion of the heating zone so that any section of the incoming fabric is progressively heated. During this initial heating, the volatile constituents of the organic size on a glass fabric are liberated. As the fabric travels into the hotter zones of the furnace, these volatile constituents ignite by auto-ignition and burn as a blue surface flame immediately adjacent the sides of the glass fabric.

One of the important concepts of the present invention is to burn the size from a glass fabric by such a surface flame. As observed in many runs, this surface flame extends over a relatively narrow horizontal band or zone. This zone is suggested in Fig. 1 as bounded by dotted lines A-A and B-B. The surface llame will appear in this zone and will extend substantially horizontally across the glass fabric. The moving fabric appears suddenly to develop this surface flame which burns until the combustion of the size is substantially complete, whereupon it is extinguished. Actually the moving glass fabric appears to the eye to be traversing a surface'- ilame zone, maintained in fixed position if the process is operating correctly. If the speed of the fabric is increased, this surface-flame zone will tend to rise in position in the heating zone. If the speed of the fabric decreases, the surfacename zone appears at a lower position. In prac tice, the speed of the fabric is controlled to main tain the surface-name zone in a fixed position. In addition, it has usually been found best to maintain this surface-flame zone in the lower half of the heating zone. If the surface-flame zone is carried into the upper half of the heating zone, somewhat erratic operation may result, par ticularly if the surface-flame zone is near the exit opening 43.

Such a surface ame can also be obtained in a horizontal heating zone but if an upright heating zone is employed it is distinctly preferable that the movement of the fabric be upward. If the movement is downward the volatile constituents tend to be removed by the natural chimney effect and, if ignition takes place, the flame tends to travel upward to the opening 43 and extinguish itself, giving erratic and non-uniform treatment of the fabric and often producing distinct color variations along the length cf the fabric.

The action played by this surface flame is not entirely understood but this type of combustion of the size undoubtedly accounts for part of: the new results obtainable with the process. Actually, the amount of size to be burned is relatively small and it is believed that the heat from this combustion, while it must impart some local ized heat to the glass fabric, does not play a major role in the setting of the glass yarns. surface flames are rather shallow but appear on opposite sides of the moving fabric at substantially thesame elevation in the heating zone.

There will be a chimney action in the heating zone I6, controlled in degree by the positions of the blocks 45, 46 and/o1' the blocks 55, 55. This action will draw fresh air continuously into the entrance opening 42 to renew or replenish the oxygen in the heating zone I6. In the treatment of glass cloth, it is essential to the invention that the oxygen content of the atmosphere in the heating zone shall be suflicient to insure the desired complete combustion of the size. In practice, the amount of oxygen in the heating zonal sh'oild preferably be greatly in excess of that actually required for the burning of the size. If desired, the oxygen content of the air can be The 6 augmented by injecting oxygen into the'heating zone but, in practice, I nd that the chimney action of an upright furnace will draw sufficient air into the heating zone to supply the oxygen requirements. Auxiliary air or oxygen may sometimes be required in a horizontal furnace. Usually, it is preferable to space the blocks 55. 56 a Wider distance than the blocks 45, 46 to con- Vtrol the oxygen supply and restrict the escape cf the action of the tension bars or rollers I2 and I3 and the intervening spreader bar I4. The weight of the fabric between the guide rolls I8 and I5 should not be suflicient to elongate or distort the strands of the fabric and it is usually desirable not to employ an excessively long heat. ing zone, particularly at high temperatures, as the tension in the fabric in the heating zone would be correspondingly increased and would be greater near the upper end of the section suspended in the heating zone. In practice, the motor 33 should not exert a tension on the fabric in the heating zone greatly above that imposed by the weight of the fabric, the tension being regulated by the elements I2, I3 and I4 to keep the fabric taut and free of whip.

For best results, the temperature of the furnace and the time of application of this temperature should be carefully correlated. The time of treatment will depend upon the length of the heating zone, e. g., its height, and the velocity of the fabric. The actions which talee place in the heating zone are, in part, the result of careful correlation of these various factors.

In fact, there are two aspects of the complete heat-treating process. In the first place, the organic size must be removed. In the second place, it is very desirable that the yarns be set to an enhanced degree. The extent to which these results are interrelated is not clearly known but it is assumed that the temperature range for setting overlaps that required to effect the autocombustion, particularly as the over-all time of heat application appears to be one factor in effecting the superior setting of the yarns.

The degree of setting is difficult to measure quantitatively, although it is a very substantial. factor in bettering the hand of the ultimate product. Quantitative results can be obtained by treating glass tape and carefully unraveling the fill yarn from a short length of the tape, sus pending this fill yarn and measuring the free hang thereof. With untreated tape, the free hang will be many times as great as with the heat-treated tape, proving the setting of the fill yarn, particularly at the edges of the tape.

It is desired that such setting be maximized and the present process has shown its distinct superiority in this regard. If the ultimate product is to have an improved hand the furnace temperature should be selected with this in mind. However, under no circumstances should the furnace temperature be so high or the speed of the fabric so slow that actual bonding of the yarns` at their intersections takes place.

ace man;

Successful, results. with glass. clothl can; be; obP

tainedi by employing, furnacey temperatures of about l.lO0-l400-F; Within this range, I- prefer to employ temperatures lof. 1125-1325" F; in most operations designed to give all of the improved results hereinbefore mentioned..

The. velocity. of the glass fabric through the heating zone: is limited only by they handling equipmentthe length ofthe. furnace and by control factors; As a practical matter, the velocity should be suchthat. the surface-flame zone remainsv in constant position and preferably remains a substantialdistance below the exit end of the. heating Zone. Thevelocity should never be so highy that. thesurfaceame does not form in the heatingA zone.

Much research: on. the present process has shown thatthebestresults are produced by correlation of` the length ofk the pass through the heating Zone,- the time inthe heatingzone, the temperature in. the heating Zone (e. g., as measured about two-thirdstheway up, as by a thermocouple B4 connected to a meter 55) and the per cent residue of organic material (by Weight, based on` the weight of the glass), this correlation for glass. cloth. being substantially within the confines. ofV the following, equation:

where:

r=per cent residue, by weight=about 0.0-0.2% t=temperature F.=about HOO-1400" F. T=time in minutes within a range in which exemplary and end values as as follows-z At about 1l00 F., T=about .0584-10 min. At about 1200" F., T=about .0383-333 min. At about 1300 T==about .0283-1157 min. At about 1409" F., T=about .0208-L min. Lzlength of pass: of fabric through heating zone,

in feet T, L and t should bev sufficiently small to prevent physical heat-bonding of the glass threads at their points of crossing in the fabric.

Performance of the process in accordance with such equation Will beV found to give satisfactory results. In the preferred practice, I prefer to limit the operation to the above equation, with the additional qualification that the slope, derived. by differentiating the equation, shall be less than .02..

No simple statement of time and temperature of treatment can bring in all of the factors involved, in view of the complexity of the interrelationships of the numerous variables. However, the later-presented specific examples will serve as a guide to indicate operations with a typical furnace.

A time-temperature relationship exists in the continuous heat processing of the glass fabric. lin order to obtain fabrics of like treatment, of equivalent ignition loss content, or of equal breaking strength, or of equal relaxation or annealing of fibers, the time of treatment or passage through the oven decreases as the temperature is increased, in the range of temperatures of 11001400 F. For example, in order to obtain fabrics equivalent in per cent ignition loss, in an oven of unit length, the time of passage through the oven at the temperature involved would vary approximately as follows:

Temperature'in F.

Genom l l i l l Another way of' stating therelationshipwouldj be to show the increase in velocity through an ovenof unit length at increasing temperatures to obtain fabrics of approximately equivalent;

breaking strength. A typical relationship is as,

follows Approximate Velocity in Ft. Per Min.

The heat-treated glass fabric issues from the heating zone at a high temperature butv cools spray the silicone or other liquid substanceI on opposite sides of the moving fabric by use ofsuitable spray nozzles 1U and H, the fabric being guided in its movementv by rollers 'i2 before passing around the drying rolls or drums 28 and 2Q. Alternatively, the coating may be applied by a dip tank, e. g., of the type to be hereinafter described.

It is desirable that the glass fabric be cooled to some extent before the coating is applied and this is accomplished during passage of the fabric through the cooling zone 25a. However, it is desirable that the coating be applied While the fabric is still at superatmospheric temperature and preferably While the fabric is above the boiling point of water. As the hot fabric is cooled, there is a marked tendency for adsorption of' atmospheric water on the glass surface which tends to hasten attrition. rI he degree or amount of adsorption increases with decreasing tempera-` ture, and reaches a maximum amount at or near room temperature, lthe adsorption being particularly pronounced at temperatures belowv the boiling point of water. For this reason, it is desirable that the coating means 59 be relatively close to the exit end of the furnace H so that the coating material can be sprayed or otherwise applied to the glass fabric while still at considerably elevated temperatures. This relationship is also desirable as hastening the subsequent drying and as requiring less external heat in the later drying step. In addition, the proximity of the coating means and the furnace minimizes handling operations. It is often important not to flex the fabric any more than necessary before the silicone coating is applied.

The silicone may be any of the numerous silicones known in the art and may be applied as a solution or emulsion, aqueous emulsions being preferred. I may use any silicone Containing alkyl, aryl, or any organic radical, in the form of fiuids, oils, gels, rubbers or even resins. Methyl silicone is preferred, applied in a 0.5-% emulsion, approximately a 5% emulsion being preferred.

I have found that this silicone treatment gives additional softness or hand or drapability to the fabric, also that it gives additional protection against self-attrition and external abrasion. It makes the fabric Water repellent, a very desirable factor in bettering the Washability and preventing actual contact between the glass and Water which would increase the abrasion between filaments or strands.

The amount of silicone emulsion thus applied is not critical but it is usually best to apply an amount substantially equal to the weight of the glass fabric.

In the subsequent drying step, the coated fabric is dried and heated to such a temperature that the silicone reacts with the glass surface. e. g., to a temperature of about 450-700 F. The test for adequacy of this treatment is merely to check the water repellency of the glass fabric.

If the treatment has been adequately performed,

water will not wet the fabric.

As a part of the process, it has unexpectedly been found that any colors in the heat-treated fabric can be lightened by washing the fabric, Without destroying its water repellency. For example, the silicone-treated fabric can be Washed in the supplementary finishing zone 21 by use of regular textile Washing equipment. Even if the silicone-coated fabric Washed with a sulfonated detergent and bleached with hypochlorite, the product being then rinsed and dried, it will not lose its Water repellency. This treatment is particularly desirable if light shades or an off-white fabric is produced and it is desired that the product be almost snow-White in color.

The coating means 69 can also be employed to apply other liquid coatings. For example, an unsaturated chromium complex or an unsaturated silicone can be applied in the housing 68, either by dipping or spraying, the fabric then being dried and cured at a temperature not to exceed 400 F. Such a fabric is eminently suitable for use as a reinforcement for low pressure laminating resins, as previously discussed.

Instead of drying the fabric on the rolls or drums 28 and 29, the drying can be effected in a suitable oven, particularly if the coating material has a solvent base.

In the supplementary finishing zone 21, numerous additional operations can be performed. For example, the previously-mentioned drying and bleaching steps can be applied in this zone or various other coatings or colors can be thus applied. In the illustrated equipment the fabric is fed to a dip tank containing a dye or other liquid, the fabric being guided by suitable rolls 16, 11, 18, 19 and 80. While some heat-resistant colors can be applied to the cloth along With the silicone treatment in the coating means 69, it is usually preferable to apply the colors in a separate step, as in the supplementary finishing zone 21. Any dyes or pigments having suitable light fastness can be employed, being sometimes applied with a resin or filming material to hold the pigment or dye on the glass surface.

The fabric continuously issuing from the dip tank 15 is preferably dried in any suitable manner. As shown, the fabric moves through a drying oven 85 to which heat is applied in any suitable way, as by an electric heating unit 86. The

fabric then moves between the previously-described take-up rolls 30 preparatory to being Wound on the roll 3l.

The continuity of the process, from heat treatment through any or all of the later steps, is particularly desirable not only from the standpoint of quickness of operation but also because handling is minimized and collection of extraneous matter on and damage to the fabric between the steps is minimized.

The following examples will serve to illustrate typical modes of operation:

Example 1 A roll of glass cloth, made by one manufacturer, style 162-44 wide (the specifications on this cloth are 015 thick, an average weight of 12.2 ounces per square yard, square or plain weave, made with 225 2/5 yarns in a weave construction of 28 counts in the warp by 16 in the fill) was run through a 6 vertical heat-treating oven at the rate of 15 feet a minute and at 1200 F. The material as it left the oven was white in color and had a volatile content or ignition loss 01 .06%. After the silicone treatment, the cloth was vastly improved in hand and had a breaking strength of of the original fabric.

A roll of fabric, made by one manufacturer, style 138-38 wide (the specifications are .007" thick, average weight of 6.7 ounces per square yard, crowfoot Weave, made With 450 2/2 yarns in a construction of 64 counts in the Warp by 60 in the ll) was processed through a heattreating oven of 6 vertical height at the rate of 35 feet per minute at a temperature of 1220 F. The fabric as it left the oven was white in color. The volatile residue content of the fabric prior to the silicone treatment was 065%. The breaking strength of the fabric Was between 60 and. of its original strength. After the silicone treatment the cloth was vastly improved in hand and had good draping and non-Wrinkling characteristics.

Example 3 A roll of fabric, made by a second manufacturer, style 12S-38" Wide (the specifications on this cloth are .007 thick, an average Weight of 6 ounces per square yard, square or plain weave, made with 225 1/3 yarns 1n a construction of 42 counts in the warp by 32 in the i-lll) Was processed through a heat-treating oven 6 high, at the rate of 8 feet a minute and at a temperature of 1200 F. The fabric as it left the oven was light beige in color. This color Was reduced to a white, after the silicone treatment was applied, by Washing with an alkyl aryl sulfonate solution and bleaching with hypochlorite. The resulta-nt product was white in color and Was greatly improved in hand Example 4 A roll .of fabric of square or plain weave and .005" thick was processed through an oven 1' in length. The oven temperature was maintained at 1l75 F. and the fabric was processed at a speed of 7 feet a minute. The processed material was White in color and the per cent residue was 0.1. The fabric had a strength equal to 60% of the original strength.

It is recognized that various changes and modifications will be apparent to those skilled in the art and need not be here enumerated in detail. Such changes and modifications can be gig, wlthout deprtig from the spirit f the invention.

Iclaim, asrnyinvention:I v ,51. yapparatus for de-fsizi'n'g "and heattreating a glass yfabric web Wliih comprises ,a vlioligytayertio'al housing, Ane'an's for pulling a glass abrio web I upwardly lthrough said v housing spaced `gild.'Ifleansly arranged :to position said fabric web in saidhousingduring its passage ihsrsthrqushserait-,imei et the baseer Said housing, a flue gas outlet at,A the top of said housing, damper means y iriczlu'dirg two spaced merribers each extending' fror'n one of the vertical sides Qaidhousne andbeine positioned alone Seid aininlethoneoueach side ofthe plane ofrsaid fabric web, and damper means. in said iuesas izutlet,including spacedmeinbers .each extending .from oneofthe .vertical .sides oisaid hous- ,ingV andbeingpositioned one on eachsideoof .f,the,planeet` tlie`v fabric Web, vboth of said damper v,means-Joe.Iig,positional to define ,a .pair Vof restricted `orifices ,i011 directing kstr-.earns of air .s .lengthwise and ...on both sidesof said fabric Aweb during passage of said Webthroughsaid housing. -,.2..,An. apparatus fonde-sizing and heat treat- .ne ,asless fabric Webwhichomprisesa .hollow vertical housing, means for pulling a glass fabric web upwardly through said housing, ,spaced guide` means arranged to position4 said fabrimweb in `saiothonsing during its passage therethrouguan air inlet-at the kbase of said housing, a. lue. gas outlet. at -the topV of said ,hous- .ing,.damper .means including. two. spaced members each extending from one of the vertical sides ofl said Vhousing andl being positioned 'along said air inlet,v one on each side `of the plane of vSaid fabric web, dampermeans in said flue gasontlet including two spaced members each 'extending from one ofthe ,verticalvsides of saidliusing and being positioned one on each iside of the planeoi the fabric Web, Vboth of saidndrnper means being positionedvto define a pair of restrictedV orifices vfor directing streams off vair lengthwise yand on b oth l sides of said fabric Web during pa,5Std-ie` Of Said Web thiosh .Seidiheilsmeendmeessdn eachpfsaid damper means for adjustably positioning, its lassociated* 'spaced members Vand thereby Vary the dimensions of said orifices.

CLARENCE KLUG.

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